Hello Barry and All,  I made another modification today, I simplified =
the method for removing and installing the damper magnet.  But that's a =
minor thing.  =20

 All day I have been tweaking the period, touchy, touchy.
Here is the latest:  With the damper removed, of course, I ONCE  got 22 =
seconds, another time I got 20.
I know little about this linkage, however I know a heck of a lot more =
than I did to start with.  The pendulum length, that which actually =
moves is 7.625"  very short indeed.  I was self-limited by the box size =
32x24x10, I just picked a number, not too big not too little.  I could =
have made it taller, and if I had it to do over I would have made it =
32x48 x12.  The reason, is a 7.625" pendulum natural period is .888 =
seconds.  (not sure of the math) and in my mockups I was getting x10 =
that period, say 9 seconds.   I repeated the mockup using different =
pendulums lengths and hinges.  I could rely on this x10 figure with very =
little trouble or effort.   I did a 42" pendulum and got 20 seconds. ( =
that box would have been to large)  as it would need to be twice the =
42",+.      But I think my box is somewhat limited.

With this linkage I can get (9 to 12 very stable), (12 to 15 unstable, =
but maybe workable) and (15 to 22 seconds, very unstable.  Presently I =
think it is set for 14?  Unless I can make improvements, and I am =
trying, that may be the max.
Again a redo, using a 32x48x12 would change the period to perhaps 28 =
seconds.

Knowing what I do now I could make it simpler and better.  To bad I out =
of money.

Now Barry, to answer your question,  To set it up and to adjust the =
period, I do this.
1 level the base.
2.square the linkage, make sure the pieces are 90 degrees.
3 remove the damper
4 move the large mass to near the center of the arm.
5 at this point the linkage still should be square and the Inverted =
pendulum pointing at 12:00
6 move the large mass toward the inverted pendulum ( the one on the =
left) until the linkage collapse and then back it off
7 move the medium mass to the left,until the linkage collapse and then =
back it off
8 do the same with the smallest mass/wing nut.
9 after each movement tweak the pitch of the box using the forward =
centering adj leg. until the Inverted pendulum returns to 12:00
10 as the period increases the arc of stability get smaller and smaller, =
from about 3" down to 1"
11 at the longer periods all the adjustments get smaller and smaller.
12 The important thing is you need to adj. the pitch and the mass, not =
just one or the other.  DO ONE THEN THE OTHER.
13  Get the highest number you can, then install the damper.
14  Check the damper and adjust if necessary.
15 I found it sometimes,necessary at this point to once again adjust the =
pitch, just in front of collapse.  Just enough to be reliable.

It is up and running now, and I will post as TCIDF.   It this point I =
really don't know where the period is, my guess it 12 to 14 seconds.  I =
hope to read the FFT and look for surface wave on the recordings.

If anyone is interest in building one, I would encourage you to do so.  =
It has been fun and interesting.  Please do contact me and I will share =
all my notes, and a list of what I would do different, and the same.

Thanks, Ted

  ----- Original Message -----=20
  From: Barry Lotz=20
  To: psn-l@.................
  Sent: Sunday, August 05, 2007 10:21 AM
  Subject: Re: More Folded Pictures


  Ted
     How did you change the sensor period? I assume you moved the =
position of the mass rather than changing the pendulum lengths.
  Regards
  Barry


  tchannel1@............ wrote:
    Hi folks,  I am still learning how to post picture.  They are =
looking better.  If you are interesting in the Folded Pendulum =
modifications and details, I added more picts to =
http://picasaweb.google.com/tchannel33  the lasted pictures in that =
Album are those with no captions.  Please notice the linkage now come to =
rest at 90 degrees, the older,captioned pictures show it favoring the =
Right hand side by 10 degrees?  The .010" wires are now visible in one =
of the pictures.  You might also notice the mass is now much closer to =
the center line, with both pendulums near vertical.


    Thanks for all of your help..........Special thanks to Chris for =
trying to improve my linkage issues.

    The picture do show some improvements, but most of the modifications =
can't be seen.   It is much better then it was, so I will keep on =
it...........Ted






Hello Barry and All,  I made =
another=20
modification today, I simplified the method for removing and installing =
the=20
damper magnet.  But that's a minor =
thing.   
 
 All day I have been tweaking the =
period,=20
touchy, touchy.
Here is the latest:  With the =
damper removed,=20
of course, I ONCE  got 22 seconds, another time I got=20
20.
I know little about this linkage, =
however I know a=20
heck of a lot more than I did to start with.  The pendulum length, =
that=20
which actually moves is 7.625"  very short indeed.  I was =
self-limited=20
by the box size 32x24x10, I just picked a number, not too big not too=20
little.  I could have made it taller, and if I had it to do over I =
would=20
have made it 32x48 x12.  The reason, is a 7.625" pendulum natural =
period is=20
..888 seconds.  (not sure of the math) and in my mockups I was =
getting x10=20
that period, say 9 seconds.   I repeated the mockup using =
different=20
pendulums lengths and hinges.  I could rely on this x10 figure with =
very=20
little trouble or effort.   I did a 42" pendulum and got 20 =
seconds. (=20
that box would have been to large)  as it would need to =
be twice=20
the 42",+.      But I think my box is =

somewhat limited.
 
With this linkage I can get (9 =
to 12 very=20
stable), (12 to 15 unstable, but maybe workable) and (15 to =
22 seconds,=20
very unstable.  Presently I think it is set for 14?  Unless I =
can make=20
improvements, and I am trying, that may be the max.
Again a redo, using a 32x48x12 would =
change the=20
period to perhaps 28 seconds.
 
Knowing what I do now I could make it =
simpler and=20
better.  To bad I out of money.
 
Now Barry, to answer your =
question,  To set it=20
up and to adjust the period, I do this.
1 level the base.
2.square the linkage, make sure the =
pieces are 90=20
degrees.
3 remove the damper
4 move the large mass to near the =
center of the=20
arm.
5 at this point the linkage still =
should be square=20
and the Inverted pendulum pointing at 12:00
6 move the large mass toward the =
inverted pendulum=20
( the one on the left) until the linkage collapse and then back it=20
off
7 move the medium mass to the =
left,until the=20
linkage collapse and then back it off
8 do the same with the smallest =
mass/wing=20
nut.
9 after each movement tweak the pitch =
of the box=20
using the forward centering adj leg. until the Inverted pendulum returns =
to=20
12:00
10 as the period increases the arc of =
stability get=20
smaller and smaller, from about 3" down to 1"
11 at the longer periods all the =
adjustments get=20
smaller and smaller.
12 The important thing is you need to =
adj. the=20
pitch and the mass, not just one or the other.  DO ONE=20
THEN THE OTHER.
13  Get the highest number you =
can, then=20
install the damper.
14  Check the damper and adjust if =

necessary.
15 I found it sometimes,necessary at =
this point to=20
once again adjust the pitch, just in front of collapse.  Just =
enough to be=20
reliable.
 
It is up and running now, and I will =
post as=20
TCIDF.   It this point I really don't know where the period =
is, my=20
guess it 12 to 14 seconds.  I hope to read the FFT and look for =
surface=20
wave on the recordings.
 
If anyone is interest in building one, =
I would=20
encourage you to do so.  It has been fun and interesting.  =
Please do=20
contact me and I will share all my notes, and a list of what I would do=20
different, and the same.
 
Thanks, Ted
 

  
----- Original Message ----- 
  From:=20
  Barry=20
  Lotz 
  
To: psn-l@.............. 
  
Sent: Sunday, August 05, 2007 =
10:21=20
  AM
  
Subject: Re: More Folded =
Pictures
  


  
Ted
  
   How did you change the sensor period? I assume you =
moved the=20
  position of the mass rather than changing the pendulum lengths.
  
Regards
  
Barry
  


tchannel1@............=
=20
  wrote:
  

    
    

    
Hi folks,  I am still learning =
how to post=20
    picture.  They are looking better.  If you are interesting =
in the=20
    Folded Pendulum modifications and details, I added more picts to =
http://picasaweb.google.com/tchannel33  the lasted pictures in that Album are those with =
no=20
    captions.  Please notice the linkage now come to rest at 90 =
degrees,=20
    the older,captioned pictures show it favoring the Right hand side by =
10=20
    degrees?  The .010" wires are now =
visible in=20
    one of the pictures.  You might also notice the mass is now =
much closer=20
    to the center line, with both pendulums near =
vertical.
    
 
    
 
    
Thanks for all of your =
help..........Special=20
    thanks to Chris for trying to improve my linkage =
issues.
    
 
    
The picture do show some =
improvements, but most=20
    of the modifications can't be seen.   It is much better =
then it=20
    was, so I will keep on=20
it...........Ted

=